MainActivity.kt

package com.example.onsizechange

import android.app.Activity
import android.content.pm.ActivityInfo
import android.content.res.Configuration
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import androidx.window.layout.WindowMetricsCalculator

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(object : View(this) {
            override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
                super.onSizeChanged(w, h, oldw, oldh)
                val widthDp = w / resources.displayMetrics.density
                Log.e("OSC", "onSizeChanged: to ($w x $h) from: ($oldw x $oldh) widthDp: $widthDp")
                if (widthDp < 600) {
                    (context as Activity).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT)
                } else {
                    (context as Activity).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED)
                }
            }

            override fun onConfigurationChanged(newConfig: Configuration?) {
                super.onConfigurationChanged(newConfig)
                val metrics = WindowMetricsCalculator.getOrCreate()
                    .computeCurrentWindowMetrics(this)

                val widthDp = metrics.bounds.width() /
                        resources.displayMetrics.density
                Log.e("OSC", "Configuration change widthDp: $widthDp")
            }
        })
    }
}